import java.util.Arrays;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 * Description:
 * User: Lily
 * Date: 2024-10-27
 * Time: 19:47
 */
public class test_3 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        while (in.hasNext()) { // 注意 while 处理多个 case
            int n = in.nextInt();
            char[] chars = in.next().toCharArray();
            int[] arr = new int[26];
            for (char c : chars) {
                arr[c - 'a']++;
            }
            char[] ret = new char[n];
            int index = 25;

            for (int i = 0; i < ; i++) {
                
            }
            while (n != 0) {

            }

            
        }
    }
}
